Automatic circuit breaker



Nov. 19, 1929. J. SACHS 1,736,372

AUTOMATI C C IRCUIT BREAKER Original Filed July 28. 1922 3 She ets-Sheet1 21 V 22 6 EQ TS) 2%] 20 NOV. 19, 1929. J s c s 1,736,372

AUTOMATIC CIRCUIT BREAKER Original Filed July 28. 1922 3 Sheets-Sheet 2xii 7% arney Nov. 19, 1929. J, s c s 1,736,372

AUTOMATI C CIRCUIT BREAKER Original Filed July 28. 19 22 s Sheets-Sheet3 Fig/A7 35 35 s1 29 31 15 o 23 l0 .1. M; (W WW fiarmgy Patented Nov.19, 1929 PATENT OFFICE .rosnrn' sscns, or wnsr m'rronn, connac'rrcnrsoromrro cmcurr nnmxna REISSUED.

Original application filed July 88,'1928,8eria1 11o. 578,125. Dividedand this application filed September.

- 1, 1988. Serial No. 808,644.

A circuit breaker constructed in accordance with the invention includesan excess current responsive means tending upon the passage of excesscurrent to efl -ect the opening of the circuit, and also includes amanually movable operating member or handle which is adapted to closethe circuit after an automatic opening thereof, the said operatingmember or handle being so connected that it cannot serve to prevent theautomatic 0 ening. The said operating member or han le may if 'desiredbe arranged to also open and close the circuit for normal switchpurposes." In the drawings the circuit breaker is illustrated as forminga part of a meter service installation but it is well adapted for useotherwise.

One object of the present invention is to provide a circuit breaker ofthe type described wherein the excess current responsive 2 meansincludes two more or less separate electro-responsive devices adapted tobe connected in different portions of the circuit and mechanicallyconnected to control the same circuit opening and closing means. As concerns this phase of the invention the two electro-responsive devices maybe of the same type or of different types as found preferable.

The two separate electro-respon'sive devices when connected in differentportions of the circuit, as for instance in the two separate legsthereof, provide protection against excess current conditions existingin one portion or leg of the circuit and not in another.

Another important obj ectof the invention is to provide a circuitbreaker of the type described wherein the excess current responsivemeans is operative by the thermal eifect and by the electro-magneticeffect of the current and tends upon the passage of excess currenttherethrough and as the result of one or both of the said effects tocause the opening of the circuit. It is well known that anelectromagnetic device will act more quickly than an electro-thermaldevice and therefore by providing both an electro-magnetic device and anelectro-thermal device I am enabled to provide for the instantaneousopening of the circuit by the electro-magnetic device when a shortcircuit exists and to effect the slightly delayed opening of the circuitby means of the electro-thermal device when a moderate overloadcondition exists.

A further object of the invention is to provide a circuit breaker of thetype described having not only two more or less separateelectro-responsive devices but also having two separate circuit breakingelements connectible in different portions of the circuit. This makes itpossible for two portions of the circuit, as for instance two legs ofthe circuit, to be broken simultaneously upon the existence of excesscurrent conditions aifecting either or both of the two excess currentresponsive devices.

Another object of the invention is to provide certain improved featuresand details of mechanical construction providing simplicity ofconstruction and reliability of operation.

Other objects of the invention will be apparent from the followingspecification and claims.

This present application constitutes a division of my copendingapplication for Electric service installation, Serial No. 578,125, filedJuly 28, 1922, issued on December 18, 1928 as 75 Patent No. 1,696,150.

In the accompanying drawings I have shown three embodiments of theinvention which have been selected as illustrative thereof. It is to beunderstood, however, that these Fig. 2 is a side view of the parts shownin Fig. 1.

Fig. 3 is\ an enlarged transverse sectional View taken along the line 33of Fig. 1.

Fig. 4 is an enlarged fragmentary sectional View taken along the lineHolt 3.

Fig. 5 is an enlarged sectional view taken along the line 55 of Fig. 3.

Fig. 6 is an enlarged fragmentary perspective view showing a detail.

Fig. 7 is an enlarged fragmentary front view somewhat similar to Fig. 1but showing an alternate embodiment of the invention.

.Fig. 8 is a transverse sectional view taken along the line 88 of Fig.7.

Fig. 9 is a fragmentary sectional View taken along the lines 9+9 ofFigs. and 8.

Fig. 10 is a fragmentary front view similar to Fig. 7 but showinganother alternate embodiment of the invention.

Fig. 11 is a transverse sectional view taken along the line -1111 ofFig. 10.

Referring to the drawings 1t Wlll be observed that the circuit breakeris shown as enclosed in a cabinet 1 having side walls 2, 2

and also having a cover 3 adapted to be sealed in closed position. Thesaid cabinet 1 1s provided with one wall, as for instance the upper endwall 4, having or adapted to havean opening therein for protectivecooperation with the terminal. chamber portlon of an electric meter suchas M. The relationship between the circuit breaker, the enclosingcabinet, and the meter form no part of the present invention and neednot be set forth in further detail, as these features are set forth indetail and claimed in my aforesaid patent.

The cabinet 1 contains an insulating or insulated'base 5, preferablythough not necessarily made in one piece and secured therein. The base 5carries the wire terminals 6, 6 connectible with the service wires andwire terminals 9, 9 connectible with the load wires, it being understoodthat the number of. such terminals depends on the number of wires orlegs of the circuit for which the apparatus is adapted. In theembodiment of the invention as shown I also provide wire terminals 7, 7and 8, 8 connectible with wires extending to and from the meter. Movableswitch connectors or contacts 10, 10 are connected respectively betweenthe pairs of terminals 8 and 9, the said connectors thus preferablybeing in the circuit after th meter. Fig. 1 shows the circuit diagramfor a common twowire circuit, the two incoming service wires beingmarked 11 and the outgoing load or house wires being marked 12. Theswitch connectors or contacts 10 are movably mounted to bridge andconnect the opposed spring clip contacts 13, 13, which are mounted onthe base and connected respectively to the terminals 8 and 9. Eachconnector or contact 10 with its associated contacts 13, 13 or both ofthe connectors 10 with their respective contacts constitute circuitopening and closing means.

The said switch connectors 10 are ringformed at their centers, as shownin Fig. 4, and both are molded into a hub 14 of insulating material,this hub being mounted on or concentric with a shaft 15 and confinedagainst endwise movement between two upstanding brackets 16, 16 securedto the base 5. The bore of the hub extends through the rings of theconnectors and is square or angular in cross-section, and the shaft 15,or at least a portion of it marked 17, conforms to the section so thatthe hub and its two switch connectors must turn with the shaft but theshaft can slide endwise or axially in the hub. The shaft 15 may beassumed to be journalled in the brackets 16, 16 and to form the supportfor the hub and connectors, such arrangement being preferred, althoughit will be apparent that these or their equivalent parts can beotherwise and variously mounted. In its normal position the shaft ispressed outwardly or to the right, to the position indicated in Fig. 3,by a coil spring 18 thrusting at one end on the adjacent bracket 16 andpinned by its other end in a cross hole drilled in the shaft. Thisspring is under torsional tension as well as under compression, so thatbesides pressing the shaft outwardly to the position shown, it alsotends to turn it on its axis and the direction of such torsional effortis such as to turn the shaft and the switch connectors 10 out of theclosed position to the open circuit position shown by the full lines inFig. 4. The contact 10 is thus biased for automatic movement out ofengagement with each of the contacts 13 to open the circuit.

By its outward pressure, the spring 18 normal y thrusts the roller crosshead 19 on the shaft 15 against or toward the disc 20 in which positionthe said cross head rollers are situated between and bear upon thestraight and axially directed edges of two opposed lugs 21 bent up fromthe edges of the disc, as shown more clearly in Fig. 6. The disc 20 willbe recognized from the drawing as forming a part of the hub structure ofthe outside crank handle or operating member 22, being designed to serveas the means which retains the hub proper in the hole in the box wallwhich forms the journal seat for the handle. It will be observed thatmovement of the crank to its upper position actuates the rock-shaftthrough the engagement of lugs 21 with rollers 19 and rotates the switchconnectors 10 in the direction to close the circuit and against thetorsion of sprin 18.

The cross hea 19 in conjunction with the lugs 21 constitute a releasablelatch, and the said parts 19 and 21 considered in conjunction with theshaft 15 constitute a releasable mechanical connection, the said latchor the said mechanical connection normally serving to prevent theautomatic movement of the movable contact to open the circuit under theinfluence of the spring 18. The said latch or mechanical connection ispreferably into the'design of the latter Outside the box wall, thehandle 22 is subject to the pressure of a spring 23 thrusting ataneccentric point 24 thereon and adapted to be carried past its deadcenter position as the handle is turned from its upper I to its lowerposition (Fig. 2).

This spring imparts a full throw to the handle in both directions and inthe handle position corresponding to the closed position of the switchconnectors, it exerts suflicient pressure on the handle to resist thetorsion of the spring 18 so that although the latter constantly acts inthe direction to open the switch, such action is prevented by thecounter-force of the 20 handle spring, more or less supplemented by thefriction of the parts. When however the handle is turned, suchresistance is removed and the spring 18 then acts to turn the shaft andthereby open the circuit. Thus the movement of the handle opens andcloses the switch connectors and thereby the handle constitutes themeans, accessible to the customer, whereby he may turn the supplycurrent on and off, as required, that is to say,

- whereby the device serves for general service-switching purposes.

It will be observed that the handle 22 can be operated for generalservice-switching purposes only in so far as its connection ismaintained with the rock shaft 15 by means of the coupler device orlatchrepresented by the disc lugs and roller cross-head, and that endwisewithdrawal of the shaft so that the rollers 19 are disengaged from thelugs will break the connection and thereby deprive the customer of anycontrol'over the switching connectors. Such dis-engagement isaccomplished automatically by the passage of a predetermined orexcessive current through the circuit and obviously leavesthe shaftunrestrained against the torsion of the spring 18, which thereuponinstantly rocks the shaft and opens the circuit. The particular meansfor thus uncoupling the switch connectors from the customers controlconsists of a current-responsive means included in thecircuit orinfluenced by the current therein and arranged to act on the couplingdevice and which may be variously designed according The beforedescribed releasable latch 21, 19 or the before described releasablemechanical connection 21, 19, 15 0: their mechanical equivalents and theelectro-responsive means cooperative therewith may be regarded ascontrolling means for the movable contact: and they will be so referredto.

In the present case as shown in Figs. 1 to 3 such automatic means is anelectro-magnet comprising two similarly wound co-axially arranged coils25 each included in one leg of the circuit, preferably ahead of themeter and between the airs of terminals 6 and 7 respectively, and ointlycreating a magnetic circuit through the internal and external fixed corepieces 26 and 26 'and the movable armature 27, which latter is mountedonor secured to the end of the shaft 15. A collar 28 is supplied at thejoint, which may be designed to serve as a stop to limit both theendwise and the rotary movement of the shaft. As shown, the collar 28has shoulders 28 of which one is shown in Fig. 3, these shouldersengaging the end of the screw holding the adjacent bracket 16.

Inasmuch as the coils 25 are permanently included in the circuit andconduct current.

as long as the switch connectors 10 are closed across the contacts 13,13 it will be apparent that the armature 27 exerts a normal pull onthe'shaft in the direction to slide it endwise through its bearings andthrough the hub 14. This pull is against the endwise thrust of thespring 18 and the latter is selected or adjusted so as to resist thearmature pull for all normal and safe current values, yielding only onthe passage of a current equal to or in excess of, some predeterminedstandard of safety.

Instantly on such displacement of the shaft,

the connector means 10 snap to their open position, the circuit isopened and, the magnetic pull having ceased, the shaft comes to restwith its rollers 19 resting on the sloped sides of the lugs 21, asindicated by the dotted lines in Fig. 5. The two connectors 10, 10 aremoved simultaneously, thus opening both legs of the circuit. It will beunderstood that this opening of both legs of the circuit will occur eventhough an excessive current is flowing in only one leg. The openingoperation takes effect without movement of the customers or usersservice-switching handle 22. In order for the user to close the circuitafter an automatic opening thereof, it is only necessary to swing theservice-switching handle 22, downwardly in the direction to cause thebevelled lugs 21 to ride under the rollers 19 until the latter snap backinto their initial position between the straight edges of the lugswhereupon the switch connectors are again placed under the customerscontrol and the return of the handle turns the switch connectors totheir closed position and the circuit is thus restored. If the cause ofthe excessive current has not been remedied, it will be quite impossiblefor the user to complete a closure of the circuit, be

cause, the energization of the magnet will Y used to produce theautomatic action. As shown the rock shaft 15, or whatever agency is usedfor effecting the opening of the circuit, is arranged to be shifted atleast in part by the thermal effect of the current. This is done bysubstituting a thermo-active device in place of the electro-magnet 25,or two thermo-active elements in place of the two coils of the magnet,each element being connected in, or associated with, one of the legs ofthe circuit, and by arranging them so that the change of form, whichresults from the heating effect of an excessive current, will move theshaft in the direction to open the coupler or otherwise release theconnectors 10 so as to open the circuit. Thermo-active elements for thispurpose may be variously shaped and organized with the other parts andcan be easily set so as to produce reliable opening action on theattainment of any dangerous or predetermined current values. In the caseillustrated each thermal element 29 is constituted of a twin spiralstrip of the same kind of bi-metallic material that is commonly used forthermostats. The centers of the two spirals are fixedly mounted on theinsulating base block 5 by suitable lugs 30 and 31 which also serve asthe wire-connecting means or terminals 6 and 7, and the opposite ends ofthe two spirals are connected together by a yoke 32 which straddles theextended end 15" of shaft 15, being insulated therefrom by a plate 33which is adapted to engage cross-pins 34 thereon. By this mounting thecurrent path is from the terminal Gthrough the adjacent spiral 29 acrossthe yoke 32 to the other spiral 29 and through the latter to theopposite terminal 7. The heating eflfect of an excessive current expandsthe spirals in the direction to uncurl them and thereby causes the yoke32 to bear, through the insulating plate 33 on the cross-pins 34 in thedirection to shift the shaft 15 endwise and open the coupler with thesame effect as'the electro-magnet above described, the shaft howeverremaining free for rotative movement under the control of the handle.

Figs. 7 and 8 show one thermal element substituted for one coil of themagnet whereas Figs. 10 and 11 show two thermal elements substitutedrespectively for the two coils of the magnet. As shown in Figs. 7 and 8the magnet and the thermal element cooperate with each other to releasethe movable contact, the magnet being adapted to act more quickly in thecase of a short circuit and the thermal element providing a slightlydelayed action in the case of a moderate overload. As shown in Figs. 10and 11 with one thermal element in each circuit leg magnetic action isentirely eliminated ample power being available from the thermalelements alone to produce reliable action.

Meter test contacts 35, 35 and 36, 36 may be rovided asshown forfacilitating the testmg of the meter, but the features of theconstruction as shown adapting it for use in meter testing are notclaimed as a part of the present invention, being set forth and claimedin my copending application for Automatic circuit breaker for meterservice, Serial No. 303,543 tiled'on even date herewith.

What I claim is:

1. An automatic circuit breaker comprising in combination, a circuitopening and closing means, a manually movable operating member, twoautomatic excess current responsive devices, means dependent upon theexcess current responsive action of either or both of the last saiddevices for automatically operating the said opening and closing meansindependently of the operating member to open the circuit, separateterminals for the two excess currents responsive devices whereby theymay be connected in different portions of the circuit, and meansenabling the operating member to effect the operation of the opening andclosing means to close the circuit after automatic opening thereof asaforesaid, the last said neans being inoperative to prevent the saidautomatic excess current responsive opening of the circuit.

2. An automatic circuit breaker comprising in combination, two electriccontacts normally in engagement with each other and one of them biasedfor automatic movement out of such engagement to open the circuit, acontrolling means for the movable contact normally operative to preventthe said automatic movement thereof and including two electroresponsivedevices each tending upon the passage of excess current therethrough toeffect the release of the said movable contact and thereby permit thesaid automatic circuit opening movement thereof, separate terminals forthe two electro-responsive devices whereby they may be connected indifferent portions of the circuit, a manually movable operating member,and means interposed between the o erating member and the movablecontact ena ling the former to return the lat ter to normal positionafter an automatic circuit opening movement, the last said means beinginoperative to prevent the said automatic excess current responsivecircuit opening movement.

7 3. An automatic circuit breaker comprising in combination, twoelectric contacts normally in engagement with each other and one of thembiased for'automatic movement out of such engagement to open thecircuit, a mechanical connection normally operative to prevent the saidautomatic movement of the movable contact, releasing means including twoelectro-responsive devices each tending upon the passage of excesscurrent therethrough to eifect the release of the said mechanicalconnection and thereby permit the said automatic circuit openingmovement of the movable contact, separate terminals for the twoelectro-responsive devices whereby they may be connected in difierentportions of the circuit, a manually movable operating member, and meansinterposed'between the operating member and the movable contact Ienabling the former to return the latter to norrent responsive action ofeither or both of the last said devices for automatically operating thesaid opening and closing means independently of theoperating member toopen the circuit, separate terminals for the two excess currentresponsive devices whereby they may be connected in difierent portionsof the circuit, and means enabling the operating memher to effect theoperation of the opening and closing means to close the circuit afterautomatic opening thereof as aforesaid and to effeet the operationthereof to both open and close the circuit for normal switchingpurposes, the last said means being inoperative to prevent the saidautomatic excess current responsive opening of the'circuit.

5. An automatic circuit breaker comprising in combination, twoelectriccontacts normally in engagement with each other and one of thembiased for automatic movement out of such engagement to open thecircuit, a manually movable operating member, controlling means for themovable contact including a releasable mechanical connection between theoperating member and the movable contact normally operative to preventthe said automatic movement of the latter and enabling the operatingmember to effect the movement of the movable contact in either directionfor the normal opening and closing of the circuit, the said controllingmeans also including two electro-responsive devices each tending uponthe passage of excess current therethrough to act upon the saidmechanical connection so as to thereby release the said movable contactand permit the said automatic circuit opening movement thereofindependently of the operating member, and separate terminals for thetwo electro-responsive devices whereby they may be connected indifferent portions of the circuit.

'6. An automatic circuit breaker compris ing in combination, a circuitopening and closing means, a manually movable operating member, excesscurrent responsive means operative b electro-thermal and electromagnetice ect, means operatively dependent upon the said current responsivemeans for automatically operating the said 0 ening and closing meansindependently of t e opcrating member to open the circuit, and meansenabling the operating member to effeet the operation of the opening andclosing means to close the circuit after automatic openin thereof asaforesaid, the last said means eing inoperative to prevent the saidautomatic excess current responsive opening of the circuit.

0 7. An automatic circuit breaker-comprismg in combination, two electriccontacts normally in engagement with each other and one of them biasedfor automatic movement out of suchengagement to open the circuit, acontrolling means for the movable contact normally operative to preventthe said automatic movement thereof and including two excess currentresponsive devices one electrothermal and the other electro-magnetic andeach tending upon the passage of excess current therethrough to eifectthe release of the said movable cont-act and thereby permit the saidautomatic circuit opening movement thereof, a manually movable operatingmember, and means interposed between the operating member and themovable contact enabling the former to' return the latter to normalposition after an automatic circuit opening movement, the last saidmeans being inoperative to prevent the said automatic excess currentresponsive circuit opening movement. 7

a 8. An automatic circuit breaker compris- 1ng in combination, twoelectric contacts normally in engagement with each other and one of thembiased for automatic movement out of such engagement to open thecircuit, a con trolling means for the movable contact including areleasable latch normally operative to prevent the said automaticmovement thereof and also including two excess current responsivedevices one electro-thermal and the other electro-magnetic and eachtending upon the passage of excess current therethrough to release thelatch and thereby per mit the automatic circuit opening movement of themovable contact, a manually movable operating member, and meansinterposed between the operating member and the movable contact enablingthe former to return the latter to normal position after anautoadditional to the mechanical connection and includingelectro-thermal and elect ro-mag; netic devices connectible inseries'with eac other and with the contacts and each tending upon thepassage of excess current therethrough to effect the release of the saidmechanical connection and thereby permit the said automatic circuitopening movement of the movable contact, a manually movable operatingmember,and means interposed between the operating member and the movablecontact enabling the former to return the latter to normal positionafter an automatic circuit opening movement, the last said means beinginoperative to prevent the said automatic circuit opening movement whenthe mechanical connection is released as aforesaid by-the releasingmeans.

10. An automatic circuit breaker comprising in combination, two electriccontacts normally in engagement with each other and one of them biasedfor automatic movement out of such engagement to open the circuit, acontrolling means for the movable contact normally operative to preventthe said automatic movement thereof and including two excess currentresponsive devices one electrothermal and the other electro-magnetic andeach tending upon the passage of excess current therethrough to effectthe release of the said movable contact and thereby permit the saidautomatic circuit opening movement thereof, separate terminals for thesaid excess current responsive devices whereby they may be connected indifferent portions of the circuit, a manually movable operating member,and means interposed between the operating member and the movablecontact enabling the former to return the latter into engagement withthe other contact after an automatic circuit opening movement, the lastsaid means being inoperative to prevent the said automatic excesscurrent responsive circuit opening movement.

11. An automatic circuit breaker comprising in combination a circuitopening and closing means, a manually movable operating member, excesscurrent responsive means operative by electro-thermal andelectromagnetic eflfect, means operatively dependent upon the saidcurrent responsive means for automatically operating the said openingand closing means independently of theoperating member to open thecircuit, and means enabling the operating member to efl'ect theoperation of the opening and closing means to close the circuit afterautomatic opening thereof as aforesaid and to effect the operationthereof to both open and close the circuit for normal switchingpurposes, the last said means being inoperative to prevent the saidautomatic excess current responsive opening of the circuit.

12. An automatic circuit breaker comprising in combination, two electriccontacts nor- 'nlally in engagement with each other and one of thembiased for automatic movement out of such engagement to open thecircuit, a manually movable operating member, and controlling means forthe movable contact including a releasable mechanical connection betweenthe operating member and the movable contact normally operative toprevent the said automatic movement of the latter and enabling theoperating member to effect the movement of the movable contact in eitherdirection for the normal opening and closing of the circuit, the saidcontrolling means also including two excess current responsive devicesone electro-thermal and the other electro-magnetic and each tending uponthe passage of excess current therethrough to act upon the saidmechanical connection so as to thereby release the said movable contactand permit the said automatic circuit opening movement thereofindependently of the operating member.

13. An automatic circuit breaker comprising in combination, two electriccontacts normally in engagement with each other and one of them biasedfor automatic movement out. of such engagement to open the circuit, amanually movable operating member, a re leasable mechanical connectionbetween the operating member and the movable contact normally operativeto prevent the said automatic movement of the latter and enabling theoperating member to effect the movement of the movable contact in eitherdirection for the normal opening and closing of the circuit, andreleasing means additional to the said mechanical connection andincluding two excess current responsive devices one electro-thermal andthe other electro-magnetic and each tending upon the passage of excesscurrent therethrough to act upon the said mechanical connection so as tothereby release the said movable contact and permit the said automaticcircuit opening movement {)hereof independently of the operating mem-14. An automatic circuit breaker comprising in combination, two circuit0 ening and closing means connectible in di erent portions of thecircuit, amanually movable operating member, two automatic excesscurrent responsive devices connectible in different portions of thecircuit, means dependent upon the excess current responsive action ofeither or both of the last said devices for automatically operating bothof the said opening and closing means independently of the operatingmember to open the circuit at two places, and means enabling theoperating member to efiect the operation of both of the opening andclosing means to close the circuit after automatic opening thereof asaforesaid,

the last saidmeans being inoperative to prevent the said automaticexcess currcnt responsive openmg of the circuit.

15. An-automatic circuit breaker comprising in combination, two circuitopening and closing means connectible in different portions of thecircuit, a manually movable operating member, excess current responsivemeans operative by electro-thermal and electro-magnetic effect, meansoperatively dependent upon the electro-thermal effect or theelectromagnetic efi'ect or both of the last said means for automaticallyoperating both of the said opening and closing means independently ofthe operating member to open the circuit at two places, and meansenabling the operating member to effect the'operation of both of theopening and closing means to close the circuit after automatic openingthereof as aforesaid and to effect the operation thereof to both openand close the circuit at two places for normal switching purposes, thelast said means being inoperative to prevent the said automatic excesscurrent responsive opening of the circuit.

16. An automatic circuit breaker comprising in combination, a shaftmovable rotatively and axially, a contact member mounted onthe shaft forrotation therewith but held against axial movement therewith, a fixedcontact with which the contact portion of the movable contact membernormally engages, a manually movable operating member, a mechanicalconnection between the o erating member and the shaft normally ena lingthe former to rotatively move the latter and thereby move the contactmember into or out of engagement with the fixed contact, the saidconnection being releasableby axial movement of the shaft, meansautomatically 0 rative upon the release of the mechanica connection asaforesaid for rotating the shaft and the contact tion as aforesaid forrotating the shaft and the contact member independently of the op memberinde endently of the operating member to disengage the contact memberfrom the fixed contact, and an electro-responsive device connectible inseries with the said contacts and servin excess current theretfirough tomove the shaft axially to effect the said release of the said mechanicalconnection.

17. An automatic circuit breaker comprising in combination, a shaftmovable rotatively and axially, a contact member mounted on the shaftfor rotation therewith but held against axial movement therewith, afixed contact with which the contact portion of the movable contactmember normally engages, a manually movable operatin member,

a mechanical connection between t e operating member and the shaft atone side of the said contacts and normally enabling the operating memberto move the shaft and thereby move the contact member into or out ofengagement with the fixed contact, the said connection being releasableby axial movement of the shaft, means automatically operative uponthe'release of'the mechanical connecupon the passage of v

